Systems and methods for migrating data

ABSTRACT

Various embodiments provide systems and methods for migrating data. One system includes a small computer system interface logical unit number (SCSI LUN) configured to store protected data, a processor, and memory configured to store a peer-to-peer remote copy (PPRC) application. The processor is configured to execute the PPRC application to modify the protection in transmitted data and received data. One method includes receiving unprotected data, utilizing a PPRC application to add protection to the data to generate protected data, and storing the protected data in a protected SCSI LUN. Another method includes receiving, at a protected SCSI LUN, a request to transmit protected data, utilizing a PPRC application to strip the protection from the protected data to generate unprotected data, and transmitting the unprotected data to an unprotected SCSI LUN.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to computing systems, and moreparticularly to, systems and methods for migrating data from anunprotected small computer system interface logical unit number (SCSILUN) to a protected SCSI LUN and migrating data from a protected SCSILUN to an unprotected SCSI LUN utilizing a peer-to-peer remote copy(PPRC) application.

2. Description of the Related Art

The T10 small computer system interface (SCSI) standard defines a DIFinformation model where a SCSI block device may be formatted with a dataintegrity field (DIF) associated with each logical block. The DIFprovides end-to-end protection and verification of the integrity of thedata from the time that the SCSI host initially writes the data.

A block device that is formatted without DIF information is referred toas including type 0 protection. A block device formatted with DIFinformation is referred to as including type 1 protection and includes ablock cyclic redundancy check (CRC), a reference tag (LBA), and anapplication-defined application tag.

As support for T10 DIF emerges, it is desirable to migrate data fromexisting volumes that have type 0 protection (i.e., do not include type1 protection) to volumes that are formatted with type 1 protection.Current systems and methods for performing this type of data migrationtypically utilize a SCSI host to perform the data migration.Specifically, the SCSI host reads all of the blocks of data from theunprotected volume, formats the blocks of data with DIF information, andthen writes the blocks of data along with the DIF information to the newvolume. In other words, the SCSI host is responsible for performing eachof the tasks related to migrating data between volumes.

SUMMARY OF THE INVENTION

Various embodiments provide systems for migrating data. One systemcomprises a small computer system interface logical unit number (SCSILUN) configured to store protected data, a processor, and memory coupledto the processor. The memory is configured to store a peer-to-peerremote copy (PPRC) application, wherein the processor is configured toexecute the PPRC application to modify the protection in transmitteddata and received data.

Other embodiments provide methods for migrating unprotected data to aprotected SCSI LUN. One method comprises receiving unprotected data froma first processor. The method further comprises utilizing, by a secondprocessor, a PPRC application to add protection to the data to generateprotected data and storing the protected data in a protected SCSI LUN.

Methods for migrating protected data to an unprotected SCSI LUN are alsoprovided. A method comprises receiving, at a protected SCSI LUN, arequest to transmit the protected data, utilizing a PPRC application tostrip the protection from the protected data to generate unprotecteddata, and transmitting the unprotected data to the unprotected SCSI LUN.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readilyunderstood, a more particular description of the invention brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is a block diagram of one embodiment of a system for migratingdata;

FIG. 2 is a block diagram of another embodiment of a system formigrating data;

FIG. 3 is a block diagram of yet another embodiment of a system formigrating data;

FIG. 4 is a flow diagram of one embodiment of a method for migratingunprotected data from an unprotected SCSI LUN to a protected SCSI LUN;and

FIG. 5 is a flow diagram of an embodiment of a method for migratingprotected data from a protected SCSI LUN to an unprotected SCSI LUN.

DETAILED DESCRIPTION OF THE DRAWINGS

The illustrated embodiments below provide systems and methods formigrating data. One system comprises a small computer system interfacelogical unit number (SCSI LUN) configured to store protected data, aprocessor, and memory coupled to the processor. The memory is configuredto store a peer-to-peer remote copy (PPRC) application, wherein theprocessor is configured to execute the PPRC application to modify theprotection in transmitted data and received data.

Other embodiments provide methods for migrating unprotected data to aprotected SCSI LUN. One method comprises receiving unprotected data froma first processor. The method further comprises utilizing, by a secondprocessor, a PPRC application to add protection to the data to generateprotected data and storing the protected data in a protected SCSI LUN.

Methods for migrating protected data to an unprotected SCSI LUN are alsoprovided. A method comprises receiving, at a protected SCSI LUN, arequest to transmit the protected data, utilizing a PPRC application tostrip the protection from the protected data to generate unprotecteddata, and transmitting the unprotected data to the unprotected SCSI LUN.

Turning now to the figures, FIG. 1 is a block diagram of one embodimentof a system 100 for migrating data. At least in the illustratedembodiment, system 100 comprises a memory 110, a SCSI LUN 120 comprisingunprotected data, a SCSI LUN 130 comprising protected data, and aprocessor 140 coupled to one another via a bus 150 (e.g., a wired and/orwireless bus).

Memory 110 may be any memory system and/or device capable of storing apeer-to-peer remote copy (PPRC) application 1110. PPRC 1110, in oneembodiment, is a protocol (e.g., computer-executable code) utilized tomirror a first SCSI LUN (e.g., a source volume) to a second SCSI LUN(e.g., a target volume).

SCSI LUN 120 may be any memory system and/or block device capable ofstoring data. In one embodiment, SCSI LUN 120 comprises unprotecteddata. In other words, SCSI LUN 120 is formatted without DIF information(e.g., includes type 0 protection). The unprotected data in SCSI LUN 120is capable of being transmitted to SCSI LUN 130 utilizing PPRCapplication 1110.

SCSI LUN 130 may be any memory system and/or device capable of storingdata. In one embodiment, SCSI LUN 130 comprises protected data. In otherwords, SCSI LUN 130 is formatted with DIF information (e.g., includestype 1 protection). Data stored in SCSI LUN 130 includes a dataintegrity field (DIF) that includes a block cyclic redundancy check(CRC), a reference tag (LBA), and an application-defined applicationtag. The protected data in SCSI LUN 130 is capable of being transmittedto SCSI LUN 120 utilizing PPRC application 1110.

Processor 140 may be any system, device, and/or device capable ofexecuting PPRC application 1110 in the background to migrate (e.g.,mirror) data between SCSI LUN 120 and SCSI LUN 130. In one embodiment,processor 140 is configured to migrate unprotected data from SCSI LUN120 to SCSI LUN 130. Specifically, processor 140 is configured toutilize PPRC application 1110 to convert the unprotected data toprotected data and store the protected data in SCSI LUN 130. In otherwords, processor 140 is configured to utilize PPRC application 1110 toadd type 1 protection to the data and store the data with type 1protection in SCSI LUN 130.

When migrating data from SCSI LUN 120 to SCSI LUN 130, processor 140 isconfigured to determine from the small computer system interface commanddescriptor block (SCSI CDB) that the data being migrated from SCSI LUN120 is not formatted with type 1 protection and that the write commandis addressed to a volume that that is formatted with type 1 protection(i.e., SCSI LUN 130). In response thereto, processor 140 is configuredto generate DIF information on the logical blocks of the data as theblocks are being written into SCSI LUN 130. The DIF informationgenerated will have good block CRC, a reference tag, and an applicationtag set to the industry standard “FFFFh”, which indicates that thevalidity of the DIF should not be checked.

When type 1 protection with a valid application tag is generated, thenthe integrity of the data from the time that the DIF information wasgenerated on SCSI LUN 130 is ensured. When a host reads the data on SCSILUN 130, a valid DIF on the logical blocks ensures that the data was notcorrupted after the data was written to SCSI LUN 130.

In an alternative embodiment, processor 140 is configured to provide aninterface that enables a user to select a value to use for theapplication tag, rather than “FFFFh.” An application tag that is notFFFFh indicates that the validity of the DIF should be checked andallows a user to check the validity of the data stored in SCSI LUN 130.In other words, enabling a user to define and/or select an applicationtag that is different than FFFFh (i.e., an application tag that isdifferent than the industry standard default application tag), allowsthe user to check the CRC of the data subsequent to reading the datafrom SCSI LUN 130.

In another embodiment, processor 140 is configured to migrate data fromSCSI LUN 130 (i.e., from a volume formatted with type 1 protection) toSCSI LUN 120 (i.e., to a volume that does not include type 1protection). That is, SCSI LUN 130 has support for the datatransformation, while SCSI LUN 120 does not support the datatransformation.

To perform the data migration, processor 140 is configured to determineif the receiving SCSI LUN (i.e., SCSI LUN 120) is formatted with DIFinformation. This determination is made when a relationship between SCSILUN 120 and SCSI LUN 130 is first established. Specifically, SCSI LUN130 issues a query to SCSI LUN 120 to determine the state of SCSI LUN120. In response to the query, SCSI LUN 120 transmits a response thatincludes a flag that indicates whether or not the secondary volume isformatted with DIF information (i.e., a flag that indicates that SCSILUN 120 is not formatted with type 1 protection) and SCSI LUN 130 storesthis information. When data is transferred from SCSI LUN 130 to SCSI LUN120, processor 140 is configured to strip the type 1 protection from thelogical blocks being transmitted from SCSI LUN 130 to SCSI LUN 120 priorto transmitting the data to SCSI LUN 120.

The following sequence is illustrative of the operation of thisembodiment of system 100. Initially, processor 140 determines that it isnecessary to issue a command to write data from SCSI LUN 130 to SCSI LUN120. Processor 140 then determines that SCSI LUN 130 is formatted withtype 1 protection and that SCSI LUN 120 is not formatted with type 1protection. Processor 140 is then configured to strip the type 1protection from the logical blocks and then transfer the logical blocksto SCSI LUN 120. Furthermore, processor 140 then strips the DIF from theblocks as processor 140 reads the data from SCSI LUN 130 and then sendsa SCSI write command with the data to SCSI LUN 120.

Although FIG. 1 illustrates system 100 as comprising one unprotectedSCSI LUN (e.g., SCSI LUN 120) and one protected SCSI LUN (SCSI LUN 130),system 100 is not limited to such. That is, various embodiments ofsystem 100 may include more than one unprotected SCSI LUN (e.g., SCSILUN 120) and/or more than one protected SCSI LUN (SCSI LUN 130) andfunction similar to the illustrated embodiment of system 100.

With reference to FIG. 2, FIG. 2 is a block diagram of anotherembodiment of a system 200 for migrating data. At least in theillustrated embodiment, system 200 comprises a computing device 210coupled to a computing device 220 via a network 230 (e.g., a wide areanetwork, a local area network, the Internet, and the like networks).

Computing device 210, which is similar to system 100 discussed abovewith reference to FIG. 1, comprises a memory 2110, a SCSI LUN 2120comprising unprotected data, a SCSI LUN 2130 comprising protected data,and a processor 2140 coupled to one another via a bus 2150 (e.g., awired and/or wireless bus).

Memory 2110 may be any memory system and/or device capable of storing aPPRC application 2112. PPRC 2112, in one embodiment, is a protocol(e.g., computer-executable code) utilized to mirror a first SCSI LUN(e.g., a source volume) to a second SCSI LUN (e.g., a target volume).

SCSI LUN 2120 may be any memory system and/or block device capable ofstoring data. In one embodiment, SCSI LUN 2120 comprises unprotecteddata. In other words, SCSI LUN 2120 is formatted without DIF information(e.g., includes type 0 protection). The unprotected data in SCSI LUN2120 is capable of being transmitted to SCSI LUN 2130 utilizing PPRCapplication 2112.

SCSI LUN 2130 may be any memory system and/or device capable of storingdata. In one embodiment, SCSI LUN 2130 comprises protected data. Inother words, SCSI LUN 2130 is formatted with DIF information (e.g.,includes type 1 protection). Data stored in SCSI LUN 2130 includes adata integrity field (DIF) that includes a block CRC, an LBA, and anapplication-defined application tag. The protected data in SCSI LUN 2130is capable of being transmitted to SCSI LUN 2120 utilizing PPRCapplication 2112.

Processor 2140 may be any system, device, and/or device capable ofexecuting PPRC application 2112 in the background to migrate (e.g.,mirror) data between SCSI LUN 2120 and SCSI LUN 2130. In one embodiment,processor 2140 is configured to migrate unprotected data from SCSI LUN2120 to SCSI LUN 2130. Specifically, processor 2140 is configured toutilize PPRC application 2112 to convert the unprotected data toprotected data and store the protected data in SCSI LUN 2130. In otherwords, processor 2140 is configured to utilize PPRC application 2112 toadd type 1 protection to the data and store the data with type 1protection in SCSI LUN 2130.

When migrating data from SCSI LUN 2120 to SCSI LUN 2130, processor 2140is configured to determine from the SCSI CDB that the data beingmigrated from SCSI LUN 2120 is not formatted with type 1 protection andthat the write command is addressed to a volume that that is formattedwith type 1 protection (i.e., SCSI LUN 2130). In response thereto,processor 2140 is configured to generate DIF information on the logicalblocks of the data as the blocks are being written into SCSI LUN 2130.The DIF information generated will have good block CRC, a reference tag,and an application tag set to the industry standard “FFFFh.”

When type 1 protection with a valid application tag is generated, thenthe integrity of the data from the time that the DIF information wasgenerated on SCSI LUN 2130 is ensured. When a host reads the data onSCSI LUN 2130, a valid DIF on the logical blocks ensures that the datawas not corrupted after the data was written to SCSI LUN 2130.

In an alternative embodiment, processor 2140 is configured to provide aninterface that enables a user to select a value to use for theapplication tag, rather than “FFFFh.” An application tag that is notFFFFh indicates that the validity of the DIF should be checked andallows a user to check the validity of the data stored in SCSI LUN 2130.In other words, enabling a user to define and/or select an applicationtag that is different than FFFFh (i.e., an application tag that isdifferent than the industry standard default application tag), allowsthe user to check the CRC of the data subsequent to reading the datafrom SCSI LUN 2130.

In another embodiment, processor 2140 is configured to migrate data fromSCSI LUN 2130 (i.e., from a volume formatted with type 1 protection) toSCSI LUN 2120 (i.e., to a volume that does not include type 1protection). That is, SCSI LUN 2130 has support for the datatransformation, while SCSI LUN 2120 does not support the datatransformation.

To perform the data migration, processor 2140 is configured to determineif the receiving SCSI LUN (i.e., SCSI LUN 2120) is formatted with DIFinformation. This determination is made when a relationship between SCSILUN 2120 and SCSI LUN 2130 is first established. Specifically, SCSI LUN2130 issues a query to SCSI LUN 2120 to determine the state of SCSI LUN2120. In response to the query, SCSI LUN 2120 transmits a response thatincludes a flag that indicates whether SCSI LUN 2120 is formatted withDIF information (i.e., a flag that indicates that SCSI LUN 2120 is notformatted with type 1 protection) and SCSI LUN 2130 stores thisinformation. When data is transferred from SCSI LUN 2130 to SCSI LUN2120, processor 2140 is configured to strip the type 1 protection fromthe logical blocks being transmitted from SCSI LUN 2130 to SCSI LUN 2120prior to transmitting the data to SCSI LUN 2120.

The following sequence is illustrative of the operation of thisembodiment of computing device 210. Initially, processor 2140 determinesthat it is necessary to issue a command to write data from SCSI LUN 2130to SCSI LUN 2120. Processor 2140 then determines that SCSI LUN 2130 isformatted with type 1 protection and that SCSI LUN 2120 is not formattedwith type 1 protection. Processor 2140 is then configured to strip thetype 1 protection from the logical blocks and then transfer the logicalblocks to SCSI LUN 2120. Furthermore, processor 2140 then strips the DIFfrom the blocks as processor 2140 reads the data from SCSI LUN 2130 andthen sends a SCSI write command with the data to SCSI LUN 2120.

Computing device 220, which is similar to system 100 discussed abovewith reference to FIG. 1, comprises a memory 2210, a SCSI LUN 2220comprising unprotected data, a SCSI LUN 2230 comprising protected data,and a processor 2240 coupled to one another via a bus 2250 (e.g., awired and/or wireless bus).

Memory 2210 may be any memory system and/or device capable of storing aPPRC application 2212. PPRC 2212, in one embodiment, is a protocol(e.g., computer-executable code) utilized to mirror a first SCSI LUN(e.g., a source volume) to a second SCSI LUN (e.g., a target volume).

SCSI LUN 2220 may be any memory system and/or block device capable ofstoring data. In one embodiment, SCSI LUN 2220 comprises unprotecteddata. In other words, SCSI LUN 2220 is formatted without DIF information(e.g., includes type 0 protection). The unprotected data in SCSI LUN2220 is capable of being transmitted to SCSI LUN 2230 utilizing PPRCapplication 2212.

SCSI LUN 2230 may be any memory system and/or device capable of storingdata. In one embodiment, SCSI LUN 2230 comprises protected data. Inother words, SCSI LUN 2230 is formatted with DIF information (e.g.,includes type 1 protection). Data stored in SCSI LUN 2230 includes adata integrity field (DIF) that includes a block CRC, an LBA, and anapplication-defined application tag. The protected data in SCSI LUN 2230is capable of being transmitted to SCSI LUN 2220 utilizing PPRCapplication 2212.

Processor 2240 may be any system, device, and/or device capable ofexecuting PPRC application 2212 in the background to migrate (e.g.,mirror) data between SCSI LUN 2220 and SCSI LUN 2230. In one embodiment,processor 2240 is configured to migrate unprotected data from SCSI LUN2220 to SCSI LUN 2230. Specifically, processor 2240 is configured toutilize PPRC application 2212 to convert the unprotected data toprotected data and store the protected data in SCSI LUN 2230. In otherwords, processor 2240 is configured to utilize PPRC application 2212 toadd type 1 protection to the data and store the data with type 1protection in SCSI LUN 2230.

When migrating data from SCSI LUN 2220 to SCSI LUN 2230, processor 2240is configured to determine from the SCSI CDB that the data beingmigrated from SCSI LUN 2220 is not formatted with type 1 protection andthat the write command is addressed to a volume that that is formattedwith type 1 protection (i.e., SCSI LUN 2230). In response thereto,processor 2240 is configured to generate DIF information on the logicalblocks of the data as the blocks are being written into SCSI LUN 2230.The DIF information generated will have good block CRC, a reference tag,and an application tag set to the industry standard “FFFFh.”

When type 1 protection with a valid application tag is generated, thenthe integrity of the data from the time that the DIF information wasgenerated on SCSI LUN 2230 is ensured. When a host reads the data onSCSI LUN 2230, a valid DIF on the logical blocks ensures that the datawas not corrupted after the data was written to SCSI LUN 2230.

In an alternative embodiment, processor 2240 is configured to provide aninterface that enables a user to select a value to use for theapplication tag, rather than “FFFFh.” An application tag that is notFFFFh indicates that the validity of the DIF should be checked andallows a user to check the validity of the data stored in SCSI LUN 2230.In other words, enabling a user to define and/or select an applicationtag that is different than FFFFh (i.e., an application tag that isdifferent than the industry standard default application tag), allowsthe user to check the CRC of the data subsequent to reading the datafrom SCSI LUN 2230.

In another embodiment, processor 2240 is configured to migrate data fromSCSI LUN 2230 (i.e., from a volume formatted with type 1 protection) toSCSI LUN 2220 (i.e., to a volume that does not include type 1protection). That is, SCSI LUN 2230 has support for the datatransformation, while SCSI LUN 2220 does not support the datatransformation.

To perform the data migration, processor 2240 is configured to determineif the receiving SCSI LUN (i.e., SCSI LUN 2220) is formatted with DIFinformation. This determination is made when a relationship between SCSILUN 2220 and SCSI LUN 2230 is first established. Specifically, SCSI LUN2230 issues a query to SCSI LUN 2220 to determine the state of SCSI LUN2220. In response to the query, SCSI LUN 2220 transmits a response thatincludes a flag that indicates whether SCSI LUN 2220 is formatted withDIF information (i.e., a flag that indicates that SCSI LUN 2220 is notformatted with type 1 protection) and SCSI LUN 2230 stores thisinformation. When data is transferred from SCSI LUN 2230 to SCSI LUN2220, processor 2240 is configured to strip the type 1 protection fromthe logical blocks being transmitted from SCSI LUN 2230 to SCSI LUN 2220prior to transmitting the data to SCSI LUN 2220.

The following sequence is illustrative of the operation of thisembodiment of computing device 220. Initially, processor 2240 determinesthat it is necessary to issue a command to write data from SCSI LUN 2230to SCSI LUN 2220. Processor 2240 then determines that SCSI LUN 2230 isformatted with type 1 protection and that SCSI LUN 2220 is not formattedwith type 1 protection. Processor 2240 is then configured to strip thetype 1 protection from the logical blocks and then transfer the logicalblocks to SCSI LUN 2220. Furthermore, processor 2240 then strips the DIFfrom the blocks as processor 2240 reads the data from SCSI LUN 2230 andthen sends a SCSI write command with the data to SCSI LUN 2220.

In addition, system 200 is capable of migrating data between computingdevice 210 and computing device 220. Specifically, system 200 is capableof migrating unprotected data from SCSI LUN 2120 to SCSI LUN 2230 andfrom SCSI LUN 2220 to SCSI LUN 2130. Furthermore, system 200 is capableof migrating protected data from SCSI LUN 2130 to SCSI LUN 2220 and fromSCSI LUN 2230 to SCSI LUN 2120.

With additional reference to processor 2140, processor 2140 is furtherconfigured to execute PPRC application 2112 to migrate (e.g., mirror)data between SCSI LUN 2220 and SCSI LUN 2130. In one embodiment,processor 2140 is configured to migrate unprotected data from SCSI LUN2220 to SCSI LUN 2130. Specifically, processor 2140 is configured toutilize PPRC application 2112 to convert the unprotected data toprotected data and store the protected data in SCSI LUN 2130. In otherwords, processor 2140 is configured to utilize PPRC application 2112 toadd type 1 protection to the data stored in SCSI LUN 2220 and store thedata with type 1 protection in SCSI LUN 2130.

When migrating data from SCSI LUN 2220 to SCSI LUN 2130, processor 2140is configured to determine from the SCSI CDB that the data beingmigrated from SCSI LUN 2220 is not formatted with type 1 protection andthat the write command is addressed to a volume that that is formattedwith type 1 protection (i.e., SCSI LUN 2130). In response thereto,processor 2140 is configured to generate DIF information on the logicalblocks of the data as the blocks are being written into SCSI LUN 2130.The DIF information generated will have good block CRC, a reference tag,and an application tag set to the industry standard “FFFFh.”

When type 1 protection with a valid application tag is generated, thenthe integrity of the data from the time that the DIF information wasgenerated on SCSI LUN 2130 is ensured. When a host reads the data onSCSI LUN 2130, a valid DIF on the logical blocks ensures that the datawas not corrupted after the data was written to SCSI LUN 2130.

In an alternative embodiment, processor 2140 is configured to provide aninterface that enables a user to select a value to use for theapplication tag, rather than “FFFFh.” An application tag that is notFFFFh indicates that the validity of the DIF should be checked andallows a user to check the validity of the data stored in SCSI LUN 2130.In other words, enabling a user to define and/or select an applicationtag that is different than FFFFh (i.e., an application tag that isdifferent than the industry standard default application tag), allowsthe user to check the CRC of the data subsequent to reading the datafrom SCSI LUN 2130.

In another embodiment, processor 2140 is further configured to migratedata from SCSI LUN 2130 (i.e., from a volume formatted with type 1protection) to SCSI LUN 2220 (i.e., to a volume that does not includetype 1 protection). That is, SCSI LUN 2130 has support for the datatransformation, while SCSI LUN 2220 does not support the datatransformation.

To perform the data migration, processor 2140 is configured to determineif the receiving SCSI LUN (i.e., SCSI LUN 2220) is formatted with DIFinformation. This determination is made when a relationship between SCSILUN 2220 and SCSI LUN 2130 is first established. Specifically, processor2140 issues a query to SCSI LUN 2220 to determine the state of SCSI LUN2220. In response to the query, SCSI LUN 2220 transmits a response thatincludes a flag that indicates whether SCSI LUN 2220 is formatted withDIF information (i.e., a flag that indicates that SCSI LUN 2220 is notformatted with type 1 protection) and SCSI LUN 2130 stores thisinformation. When data is transferred from SCSI LUN 2130 to SCSI LUN2220, processor 2140 is configured to strip the type 1 protection fromthe logical blocks being transmitted from SCSI LUN 2130 to SCSI LUN 2220prior to transmitting the data to SCSI LUN 2220.

The following sequence is illustrative of the operation of thisembodiment of processor 2140. Initially, processor 2140 determines thatit is necessary to issue a command to write data from SCSI LUN 2130 toSCSI LUN 2220. Processor 2140 then determines that SCSI LUN 2130 isformatted with type 1 protection and that SCSI LUN 2220 is not formattedwith type 1 protection. Processor 2140 is then configured to strip thetype 1 protection from the logical blocks and then transfer the logicalblocks to SCSI LUN 2220. Furthermore, processor 2140 then strips the DIFfrom the blocks as processor 2140 reads the data from SCSI LUN 2130 andthen sends a SCSI write command with the data to SCSI LUN 2220.

With reference to an additional embodiment of processor 2240, processor2240 is further configured to execute PPRC application 2212 to migrate(e.g., mirror) data between SCSI LUN 2220 and SCSI LUN 2230. In oneembodiment, processor 2240 is configured to migrate unprotected datafrom SCSI LUN 2120 to SCSI LUN 2230. Specifically, processor 2240 isconfigured to utilize PPRC application 2212 to convert the unprotecteddata to protected data and store the protected data in SCSI LUN 2230. Inother words, processor 2240 is configured to utilize PPRC application2212 to add type 1 protection to the data stored in SCSI LUN 2220 andstore the data with type 1 protection in SCSI LUN 2230.

When migrating data from SCSI LUN 2120 to SCSI LUN 2230, processor 2240is configured to determine from the SCSI CDB that the data beingmigrated from SCSI LUN 2120 is not formatted with type 1 protection andthat the write command is addressed to a volume that that is formattedwith type 1 protection (i.e., SCSI LUN 2230). In response thereto,processor 2240 is configured to generate DIF information on the logicalblocks of the data as the blocks are being written into SCSI LUN 2230.The DIF information generated will have good block CRC, a reference tag,and an application tag set to the industry standard “FFFFh.”

When type 1 protection with a valid application tag is generated, thenthe integrity of the data from the time that the DIF information wasgenerated on SCSI LUN 2230 is ensured. When a host reads the data onSCSI LUN 2230, a valid DIF on the logical blocks ensures that the datawas not corrupted after the data was written to SCSI LUN 2230.

In an alternative embodiment, processor 2240 is configured to provide aninterface that enables a user to select a value to use for theapplication tag, rather than “FFFFh.” An application tag that is notFFFFh indicates that the validity of the DIF should be checked andallows a user to check the validity of the data stored in SCSI LUN 2230.In other words, enabling a user to define and/or select an applicationtag that is different than FFFFh (i.e., an application tag that isdifferent than the industry standard default application tag), allowsthe user to check the CRC of the data subsequent to migrating readingthe data from SCSI LUN 2230.

In another embodiment, processor 2240 is further configured to migratedata from SCSI LUN 2230 (i.e., from a volume formatted with type 1protection) to SCSI LUN 2220 (i.e., to a volume that does not includetype 1 protection). That is, SCSI LUN 2230 has support for the datatransformation, while SCSI LUN 2120 does not support the datatransformation.

To perform the data migration, processor 2240 is configured to determineif the receiving SCSI LUN (i.e., SCSI LUN 2120) is formatted with DIFinformation. This determination is made when a relationship between SCSILUN 2120 and SCSI LUN 2230 is first established. Specifically, processor2240 issues a query to SCSI LUN 2120 to determine the state of SCSI LUN2220. In response to the query, SCSI LUN 2220 transmits a response thatincludes a flag that indicates whether SCSI LUN 2120 is formatted withDIF information (i.e., a flag that indicates that SCSI LUN 2120 is notformatted with type 1 protection) and SCSI LUN 2230 stores thisinformation. When data is transferred from SCSI LUN 2230 to SCSI LUN2120, processor 2240 is configured to strip the type 1 protection fromthe logical blocks being transmitted from SCSI LUN 2230 to SCSI LUN 2120prior to transmitting the data to SCSI LUN 2120.

The following sequence is illustrative of the operation of thisembodiment of processor 2240. Initially, processor 2240 determines thatit is necessary to issue a command to write data from SCSI LUN 2230 toSCSI LUN 2120. Processor 2240 then determines that SCSI LUN 2230 isformatted with type 1 protection and that SCSI LUN 2120 is not formattedwith type 1 protection. Processor 2240 is then configured to strip thetype 1 protection from the logical blocks and then transfer the logicalblocks to SCSI LUN 2120. Furthermore, processor 2240 then strips the DIFfrom the blocks as processor 2240 reads the data from SCSI LUN 2230 andthen sends a SCSI write command with the data to SCSI LUN 2120.

Although FIG. 2 illustrates computing device 210 as comprising oneunprotected SCSI LUN (e.g., SCSI LUN 2120) and one protected SCSI LUN(SCSI LUN 2130), computing device 210 is not limited to such. That is,various embodiments of computing device 210 may include more than oneunprotected SCSI LUN (e.g., SCSI LUN 2120) and/or more than oneprotected SCSI LUN (SCSI LUN 2130) and function similar to theillustrated embodiment of computing device 210.

In addition, Although FIG. 2 illustrates computing device 220 ascomprising one unprotected SCSI LUN (e.g., SCSI LUN 2220) and oneprotected SCSI LUN (SCSI LUN 2230), computing device 220 is not limitedto such. That is, various embodiments of computing device 220 mayinclude more than one unprotected SCSI LUN (e.g., SCSI LUN 2220) and/ormore than one protected SCSI LUN (SCSI LUN 2230) and function similar tothe illustrated embodiment of computing device 220 as well as howcomputing device 220 operates in conjunction with computing device 210.

With reference to FIG. 3, FIG. 3 is a block diagram of anotherembodiment of a system 300 for migrating data. At least in theillustrated embodiment, system 300 comprises a computing device 310coupled to a computing device 320 via a network 330 (e.g., a wide areanetwork, a local area network, the Internet, and the like networks).

Computing device 310 comprises a memory 3110, a SCSI LUN 3120 comprisingunprotected data, and a processor 3140 coupled to one another via a bus3150 (e.g., a wired and/or wireless bus). Memory 3110 may be any memorysystem and/or device capable of storing a peer-to-peer remote copy(PPRC) application 3112. PPRC 3112, in one embodiment, is a protocol(e.g., computer-executable code) utilized to migrate (or mirror)unprotected data stored in SCSI LUN 3120 (e.g., a source volume) to aSCSI LUN 3230 (e.g., a target volume). Furthermore, PPRC 3212, whenexecuted by processor 3140, is configured to receive unprotected datafrom SCSI LUN 3230 and store the unprotected data in SCSI LUN 3120

SCSI LUN 3120 may be any memory system and/or block device capable ofstoring data. In one embodiment, SCSI LUN 3120 comprises unprotecteddata. In other words, SCSI LUN 3120 is formatted without DIF information(e.g., includes type 0 protection). The unprotected data in SCSI LUN3120 is capable of being transmitted to computing device 320 and datafrom computing device 320 is capable of being transmitted to SCSI LUN3120.

Processor 3140 may be any system, device, and/or device capable ofcommunicating with and executing PPRC 3112 to migrate (e.g., mirror)data between computing device 310 and computing device 320.Specifically, processor 3140 is configured to transmit unprotected datafrom SCSI LUN 3120 to computing device 320 and receive unprotected datafrom computing device 320 for storage in SCSI LUN 3120.

Computing device 320 comprises a memory 3210, a SCSI LUN 3230 comprisingprotected data (e.g., data with DIF information), and a processor 3240coupled to one another via a bus 3250 (e.g., a wired and/or wirelessbus). Memory 3210 may be any memory system and/or device capable ofstoring a protection module 3211 (e.g., an application,computer-executable code, and/or a computer program) capable of addingtype 1 protection to unprotected data (e.g., data including type 0protection or data without DIF information) and a PPRC 3212.

SCSI LUN 3230 may be any memory system and/or device capable of storingdata. In one embodiment, SCSI LUN 3230 comprises protected data. Inother words, SCSI LUN 3230 is formatted with DIF information (e.g.,includes type 1 protection). Data stored in SCSI LUN 3230 includes adata integrity field (DIF) that includes a block CRC, an LBA, and anapplication-defined application tag. The protected data in SCSI LUN 3230is capable of being transmitted to SCSI LUN 3220 utilizing PPRCapplication 3212.

Processor 3240 may be any system, device, and/or device capable ofexecuting protection module 3211 and PPRC application 3212 in thebackground to migrate (e.g., mirror) data between SCSI LUN 3230 and SCSILUN 3120. In one embodiment, processor 3240 is configured to migrateunprotected data from SCSI LUN 3120 to SCSI LUN 3230. Specifically,processor 3240 is configured to utilize protection module 3211 toconvert the unprotected data to protected data and store the protecteddata in SCSI LUN 3230. In other words, processor 3240 is configured toutilize protection module 3211 to add type 1 protection to theunprotected data and store the data with type 1 protection in SCSI LUN3230.

When migrating data from SCSI LUN 3120 to SCSI LUN 3230 utilizingprotection module 3211, processor 3240 is configured to determine fromthe SCSI CDB that the data being migrated from SCSI LUN 3120 is notformatted with type 1 protection and that the write command is addressedto a volume that that is formatted with type 1 protection (i.e., SCSILUN 3230). In response thereto, processor 3240 is configured to generateDIF information on the logical blocks of the data as the blocks arebeing written into SCSI LUN 3230. The DIF information generated willhave a good block CRC, a reference tag, and an application tag set tothe industry standard “FFFFh.”

When type 1 protection with a valid application tag is generated, theintegrity of the data from the time that the DIF information wasgenerated on SCSI LUN 3230 is ensured. In other words, when a host readsthe data on SCSI LUN 3230, a valid DIF on the logical blocks ensuresthat the data was not corrupted after the data was written to SCSI LUN3230.

In an alternative embodiment, processor 3240 is configured to provide aninterface that enables a user to select a value to use for theapplication tag, rather than “FFFFh.” An application tag that is notFFFFh indicates that the validity of the DIF should be checked andallows a user to check the validity of the data stored in SCSI LUN 3230.In other words, enabling a user to define and/or select an applicationtag that is different than FFFFh (i.e., an application tag that isdifferent than the industry standard default application tag), allowsthe user to check the CRC of the data subsequent to reading the datafrom SCSI LUN 3230.

In another embodiment, processor 3240 is configured to utilize PPRCE3212 to migrate data from SCSI LUN 3230 (i.e., from a volume formattedwith type 1 protection) to SCSI LUN 3120 (i.e., to a volume that doesnot include type 1 protection). That is, SCSI LUN 3230 has support forthe data transformation, while SCSI LUN 3120 does not support the datatransformation.

To perform the data migration, processor 3240 is configured to determineif the receiving SCSI LUN (i.e., SCSI LUN 3120) is formatted with DIFinformation. This determination is made when a relationship between SCSILUN 3120 and SCSI LUN 3230 is first established. Specifically, processor3240 issues a query to SCSI LUN 3120 to determine the state of SCSI LUN3120. In response to the query, SCSI LUN 3120 transmits a response thatincludes a flag that indicates whether SCSI LUN 3120 is formatted withDIF information (i.e., a flag that indicates that SCSI LUN 3120 is notformatted with type 1 protection) and processor 3240 stores thisinformation. When data is transferred from SCSI LUN 3230 to SCSI LUN3120, processor 3240 is configured to strip the type 1 protection fromthe logical blocks being transmitted from SCSI LUN 3230 to SCSI LUN 3120prior to transmitting the data to SCSI LUN 3120 and utilize PPRC 3212 tomigrate the data to SCSI LUN 3120.

The following sequence is illustrative of the operation of thisembodiment of system 300. Initially, processor 3240 determines that itis necessary to issue a command to write data from SCSI LUN 3230 to SCSILUN 3120. Processor 3240 then determines that SCSI LUN 3230 is formattedwith type 1 protection and that SCSI LUN 3120 is not formatted with type1 protection. Processor 3240 is then configured to strip the type 1protection from the logical blocks and then transfer the logical blocksto SCSI LUN 3120. Furthermore, processor 3240 then strips the DIF fromthe blocks as processor 3240 reads the data from SCSI LUN 3230 and thenutilizes PPRC 3212 to send a SCSI write command with the now unprotecteddata to SCSI LUN 3120.

Although FIG. 3 illustrates computing device 310 as comprising oneunprotected SCSI LUN (e.g., SCSI LUN 3120), computing device 310 is notlimited to such. That is, various embodiments of computing device 310may include more than one unprotected SCSI LUN (e.g., SCSI LUN 3120) andfunction similar to the illustrated embodiment of computing device 310.

Although FIG. 3 illustrates computing device 320 as comprising oneprotected SCSI LUN (SCSI LUN 3230), computing device 320 is not limitedto such. That is, various embodiments of computing device 320 mayinclude more than one protected SCSI LUN (SCSI LUN 3230) and functionsimilar to the illustrated embodiment of computing device 320 as well ashow computing device 320 operates in conjunction with computing device310.

With reference now to FIG. 4, FIG. 4 is a flow diagram of one embodimentof one embodiment of a method 400 for migrating unprotected data from anunprotected SCSI LUN (e.g., SCSI LUN 120, SCSI LUN 2120, SCSI LUN 2220,and SCSI LUN 3120) to a protected SCSI LUN (e.g., SCSI LUN 130, SCSI LUN2130, SCSI LUN 2230, and SCSI LUN 3230). At least in the illustratedembodiment, method 400 begins by receiving, from the unprotected SCSILUN, data with type 0 protection (i.e., unprotected data) (block 410).

Method 400 further comprises utilizing, by the protected SCSI LUN, aPPRC application to add type 1 protection to the data to generateprotected data (block 420) and storing the protected data in theprotected SCSI LUN (block 430). The protected SCSI LUN executes the PPRCin the background so that other functions of, for example, system 100,system 200, and system 300 may be performed in the foreground.

In one embodiment, the protected SCSI LUN and the unprotected SCSI LUNcomprised within a same computing device (see e.g., system 100 in FIG.1). In another embodiment, the protected SCSI LUN and the unprotectedSCSI LUN are comprised within different computing devices (see e.g.,system 200 in FIG. 2 and system 300 in FIG. 3).

In various embodiments, modifying a value in the application tag suchthat the value is different than an industry standard default value forprotected data (block 440). That is, method 400 further comprises addingthe type 1 DIF information (see block 420) with an application tag ofFFFFh when a user-defined value is not set or generating and addingvalid type 1 DIF information using a user-defined application tag valueif the application tag value was set by a user.

Method 400 further comprises checking a CRC for the protected data whena request to read and/or migrate the protected data is received (block450). That is, the CRC is checked when the application tag value is avalue other than FFFFh to ensure the integrity of the data in theprotected SCSI LUN.

Referring now to FIG. 5, FIG. 5 is a flow diagram of one embodiment of amethod 500 for migrating protected data from a protected SCSI LUN (e.g.,SCSI LUN 130, SCSI LUN 2130, SCSI LUN 2230, and SCSI LUN 3230) to anunprotected SCSI LUN (e.g., SCSI LUN 120, SCSI LUN 2120, SCSI LUN 2220,and SCSI LUN 3220). At least in the illustrated embodiment, method 500begins by receiving, at the protected SCSI LUN, a request to transmitthe protected data (block 510).

In one embodiment, method 500 further comprises checking a CRC for theprotected data in response to receiving the request (block 520). The CRCis checked to determine if the protection data is valid when the DIFincludes a value other than FFFFh.

Method 500 further comprises utilizing, by a processor, a PPRCapplication to strip the protection from the protected data (block 530)and transmit the unprotected data to the unprotected SCSI LUN (block540). In one embodiment, the protected SCSI LUN and the unprotected SCSILUN are comprised within the same computing device (e.g., system 100 inFIG. 1. In another embodiment, the protected SCSI LUN and theunprotected SCSI LUN are comprised within different computing devices(see system 200 in FIG. 2 and system 300 in FIG. 3).

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention, it being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims and their legal equivalents.

As will be appreciated by one of ordinary skill in the art, aspects ofthe present invention may be embodied as a system, method, or computerprogram product. Accordingly, aspects of the present invention may takethe form of an entirely hardware embodiment, an entirely softwareembodiment (including firmware, resident software, micro-code, etc.) oran embodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module,” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer-readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer-readable medium(s) may beutilized. The computer-readable medium may be a computer-readable signalmedium or a physical computer-readable storage medium. A physicalcomputer readable storage medium may be, for example, but not limitedto, an electronic, magnetic, optical, crystal, polymer, electromagnetic,infrared, or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. Examples of a physical computer-readablestorage medium include, but are not limited to, an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk,RAM, ROM, an EPROM, a Flash memory, an optical fiber, a CD-ROM, anoptical processor, a magnetic processor, or any suitable combination ofthe foregoing. In the context of this document, a computer-readablestorage medium may be any tangible medium that can contain, or store aprogram or data for use by or in connection with an instructionexecution system, apparatus, or device.

Computer code embodied on a computer-readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wired, optical fiber cable, radio frequency (RF), etc., or any suitablecombination of the foregoing. Computer code for carrying out operationsfor aspects of the present invention may be written in any staticlanguage, such as the “C” programming language or other similarprogramming language. The computer code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, or communication system, including, but notlimited to, a local area network (LAN) or a wide area network (WAN),Converged Network, or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).

Aspects of the present invention are described above with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable medium that can direct a computer, other programmabledata processing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer, other programmable data processing apparatus, orother devices to cause a series of operational steps to be performed onthe computer, other programmable apparatus or other devices to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the above figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

While one or more embodiments of the present invention have beenillustrated in detail, one of ordinary skill in the art will appreciatethat modifications and adaptations to those embodiments may be madewithout departing from the scope of the present invention as set forthin the following claims.

1. A system for migrating data, comprising: a first small computersystem interface logical unit number (SCSI LUN) configured to storeprotected data; a processor; and memory coupled to the processor, thememory configured to store a peer-to-peer remote copy (PPRC)application, wherein the processor is configured to execute the PPRCapplication to modify protection in transmitted data and received data.2. The system of claim 1, wherein the processor is further configuredto: receive data that is unprotected; utilize the PPRC to add protectionto the data to generate protected data; and store the protected data inthe first SCSI LUN.
 3. The system of claim 2, wherein the processor isconfigured to receive the data from a second SCSI LUN, the first SCSILUN and the second SCSI LUN comprised within a same computing device. 4.The system of claim 2, wherein the processor is configured to receivethe data from a second SCSI LUN, the first SCSI LUN and the second SCSILUN comprised within different computing devices.
 5. The system of claim1, wherein the processor is configured to execute the PPRC in thebackground to add the protection to the data.
 6. The system of claim 2,wherein the data comprises a data integrity field, the processor furtherconfigured to modify a value in the data integrity field such that thevalue is different than an industry standard default value for protecteddata subsequent to adding the protection.
 7. The system of claim 6,wherein the processor is further configured to check a CRC for theprotected data when the processor receives a request to read theprotected data.
 8. The system of claim 1, wherein the first SCSI LUN isconfigured to store data the processor is further configured to: receivea request to transmit the protected data; utilize the PPRC to stripprotection from the protected data to generate unprotected data; andtransmit the unprotected data to a second SCSI LUN.
 9. The system ofclaim 8, wherein the processor is configured to receive the data from asecond SCSI LUN, the first SCSI LUN and the second SCSI LUN comprisedwithin a same computing device.
 10. The system of claim 8, wherein theprocessor is configured to receive the data from a second SCSI LUN, thefirst SCSI LUN and the second SCSI LUN comprised within differentcomputing devices.
 11. A method for migrating unprotected data to aprotected small computer system interface logical unit number (SCSILUN), comprising: receiving, from a first processor, data that isunprotected; utilizing, by a second processor, a peer-to-peer remotecopy (PPRC) application to add protection to the data to generateprotected data; and storing the protected data in the protected SCSILUN.
 12. The method of claim 11, wherein receiving comprises receivingthe unprotected data from an unprotected SCSI LUN, the protected SCSILUN and the unprotected SCSI LUN comprised within a same computingdevice.
 13. The method of claim 11, wherein receiving comprisesreceiving the unprotected data from an unprotected SCSI LUN, theprotected SCSI LUN and the unprotected SCSI LUN comprised withindifferent computing devices.
 14. The method of claim 11, whereinutilizing the PPRC comprises executing the PPRC in the background to addthe protection to the unprotected data.
 15. The method of claim 11,wherein the unprotected data comprises a data integrity field, themethod further comprising modifying a value in the data integrity fieldsuch that the value is different than an industry standard default valuefor protected data subsequent to adding the protection.
 16. The methodof claim 15, further comprising checking a CRC for the protected datawhen a request to migrate the protected data is received.
 17. A methodfor migrating protected data from a protected small computer systeminterface logical unit number (SCSI LUN) to an unprotected SCSI LUN,comprising: receiving, at the protected SCSI LUN, a request to transmitthe protected data; utilizing, by a processor, a peer-to-peer remotecopy (PPRC) application to strip protection from the protected data togenerate unprotected data; and transmitting the unprotected data to theunprotected SCSI LUN.
 18. The method of claim 17, wherein the protectedSCSI LUN and the unprotected SCSI LUN are comprised within a samecomputing device.
 19. The method of claim 17, wherein the protected SCSILUN and the unprotected SCSI LUN are comprised within differentcomputing devices.
 20. The method of claim 17, further comprisingchecking a CRC for the protected data to determine if the protection isvalid in response to receiving the request.